Mobile drafting apparatus with support skids and removable cord pulleys



March 26, 1968 C. E. JUSTIS, SR

MOBILE DRAFTING APPARATUS WITH SUPPORT SKIDS AND REMOVABLE CORD PULLEYS Filed Dec. 22, 1966 2 Sheets-Sheet 1 ATTORNEYS March 26, 1968 c. E.JUST1S, SR 3,374,546

MOBILE DRAFTING APPARATUS WITH SUPPORT sxws AND REMOVABLE CORD PULLEYS Filed Dec. 22, 1966 2 SheetsShee(. 2-

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United States Patent Office 3,374,546 Patented Mar. 26, 1968 3,374,546 IVIOBILE DRAFHNG APPARATUS WITH SUPZORT SKIDS AND REMGVABLE CORD PULLEYS Charles E. Justis, Sr., 825 Greenwood Road, Jenkintown, Pa. 19046 Filed Dec. 22, 1966, Ser. No. 603,869 6 Claims. (CI. 3380) ABSTRACT OF THE DISCLOSURE A straightedge blade body having parallel guiding edges includes two pulleys at each end thereof which engage the fixed guide cable. These guide pulleys may be mounted either in a substantially parallel relationship to the underlying drafting board or at an angle thereto. In a first form, the mounting means for the pulleys includes a rivet having a head thereof disposed within a cup washer the undersurface of which slides on the supporting surface to provide a skid means to facilitate movement. In another form of the invention, mounting means includes a headed member having a threaded bore therewithin and a stud member threaded into this threaded bore, the head of the stud member engaging an underlying surface. In further modifications, a tapered wedge-shaped pedestal is provided for supporting the pulleys substantially parallel with the drafting board. Additional skid members are attached to the undersurface of the blade body. In a further modified form, a snap-on skid member is provided including integral depending skid portions and having opposite ends adapted to snap onto the associated blade body.

This invention relates generally to the class of geometrical instruments and is directed particularly to improvements in drafting apparatus of the type disclosed in my issued Patents 3,106,783 of Oct. 15, 1953, and 3,251,- 131 of May 17, 1966.

The drafting apparatus of the present invention corresponds in certain respects to the apparatus disclosed in my prior patent in the employment of a straightedge unit associated with a means connecting it with a supporting drawing board or other surface, whereby such straightedge unit may be easily moved back and forth relative to the working surface of the drawing board for the purpose of drawing or laying out parallel lines thereon.

In the use of the straightedge in association with the means for supporting it on the board for movement back and forth as above stated, the straightedge must have sliding contact with the board or with the sheet of material lying thereunder upon which lines are to be laid out and such contact may include the entire underface of the straightedge or merely portions adjacent to the longitudinal edges thereof. In either case it will be readily obvious that such sliding contact between the straightedge and the underlying surface offers a certain frictional resistance to the movement of the straightedge. Accordingly, it is an important object of the present invention to provide an improved mobile drafting apparatus wherein the straightedge is provided with means providing a sliding or skid contact with the underlying surface of the drawing board or a sheet of paper or other material such as tracing cloth, lying thereon, whereby frictional resistance to the movement of the straightedge is reduced to a minimum.

A further object of such an invention is to provide combined supporting and friction reducing means for a straightedge wherein such means is of a form to provide a very small area of contact with the drawing board surface or sheet material lying thereon.

It is a further object of the invention to provide in apparatus of the character stated, a straightedge unit carrying upon its undersurface skid forming elements or members for sliding contact with the drawing board surface or sheet material lying thereon and for maintaining the major portion of the undersurface of the straightedge raised from the underlying surface at the longitudinal edges of the straightedge and for a short distance inwardly therefrom whereby in the use of a ruling pen the possibility of ink being drawn from the ruling pen to the undersurface of the straightedge and consequently blotting the sheet on which the straightedge rests, is entirely avoided.

A further object of the invention is to provide skid means for the purpose stated formed of a suitable plastic, such as Teflon, for example, which has the characteristic of providing a substantially frictionless engagement with a supporting surface.

Still another object of the invention is to provide a novel skid means for a straightedge which may be easily and quickly applied to and removed from the straightedge for cleaning, when necessary, or for replacement if and when desired, and which may be formed of metal or plastic and wherein such skid forming means is contoured to have a point or spot contact with the underlying supporting surface.

In the present improved apparatus the means connecting the straightedge unit with the underlying supporting surface whereby such unit may be easily moved back and forth, embodies the use of flexible cords and pulleys operating in a similar manner to those disclosed in prior Patent 3,251,131 and a further object of the present invention is directed to improvements in the cord pulleys and more particularly to the manner in which the same are mounted upon the straightedge unit.

In the apparatus of the present invention, it is an object to provide improved pivot posts for the cord pulleys and means for attaching such pivot posts to the straightedge unit. I

A further object of the invention with regard to the mounting means for the cord pulleys, is to provide a novel manner of securing the pulley pivot posts to the straightedge unit whereby the pulleys can be removed and replaced easily and quickly if this should become necessary.

Other objects and many attendant advantages of the invention will become more apparent when considered in connection with the specification and accompanying drawings, wherein:

FIG. 1 is a view in top plan of the mobile drafting apparatus of the present invention, with portions of the same broken away;

FIG. 2 is a sectional view on an enlarged scale taken substantially along line 2-2 of FIG. 1 looking in the direction of the arrows;

FIG. 3 is a sectional view taken substantially along line 33 of FIG. 2 looking in the direction of the arrows;

FIG. 4 is a bottom view of the structure shown in FIG. 3 taken substantially along line 44 looking in the direction of the arrows and being on a reduced scale;

FIG. 5 is a sectional view taken substantially along line 55 of FIG. 3 looking in the direction of the arrows and being on a reduced scale;

FIG. 6 is a top perspective view illustrating a snap-on skid member according to the present invention;

FIG. 7 is a sectional view taken substantially along line 77 of FIG. 6 looking in the direction of the arrows;

FIG. 8 is a sectional view through a portion of the apparatus illustrating a modified form of the invention;

FIG. 9 is a view similar to FIG. 8 illustrating a further modification of the invention; and

FIG. 10 is a sectional view similar to FIG. 9 showing a still further modified form of the invention.

Referring now more particularly to the drawings wherein like reference numerals designate corresponding parts throughout the several views, the numeral in FIG. 1 generally designates a conventional drafting board upon which is shown a sheet 12 which may be of drawing paper, tracing cloth or the like.

The straightedge unit is generally designated 16 and in the present form of the apparatus this unit is maintained in place upon the drawing board and controlled in its 'movements, or in the movement which may be imparted thereto by the draftsman, back and forth between the top and bottom edges of the board in' a maintained parallel relationship with the said top and bottom edges in the same manner as in my Patent 3,251,131.

The strand 14 which retains the straightedge unit in position may be a single continuous strand or use may be made of two separate strands as disclosed in Patent 3,106,783.

In the present apparatus, a single continuous strand 14 is employed. Four fixed members 18 are provided on the surface of the board, one of each of such members being located adjacent to a corner of the board. The strand 14 is attached to the board by means of the fixed members 18.

The fixed members 18 may be ordinary thumb tacks or other suitable type of pins by means of which the strand can be maintained in place under some tension, the strand being in the form of a cord of conventional form, a chain or wire cable or a synthetic resin filament of suitable weight.

The st-raightedge lblade body 20 is of substantial width and of a length to extend substantially entirely across the full width of the board 10 as shown in FIG. 1.

The longitudinal edges 22 of the blade body 20 are parallel with one another and form the guide or scribing edges for laying out lines extending transversely of the drawing sheet 12 which is secured upon the surface of the board upon which the straightedge blade is positioned.

The straightedge blade here illustrated is of the type in which the underface is plane throughout from one edge 22 to the opposite edge.

The illustrated blade body 20 has a top surface formed with oppositely inclined flat faces or areas 24 which slope down toward the edges 22. At the high sides of these faces or areas they are separated by a narrow flat top space or area 26 which extends a short distance longitudinally of the blade from each end thereof.

The central part of the top of the blade body has formed therein and longitudinally thereof the relatively wide channel 28. This channel is approximately the same width as the flat middle top face 26.

The channel 28 is of dovetail cross-sectional contour whereby the opposite sides thereof have the undercut wall surfaces 30.

The channel 28 terminates at each end a substantial distance short of the end of the blade or, that is, the end of the top face or area 26.

At each end of the blade there are mounted two grooved pulleys 32 around which the strand 14 is trained.

The pulleys 32 of each pair are disposed on opposite sides of the fiat or top face or area 26.

In one embodiment of the invention each of these pulleys 32 is supported upon the inclined surface 24 of the blade as shown in FIG. 2.

The pulleys 32 are preferably formed of nylon, Teflon or other suitable plastic material.

The pulleys 32 are each maintained in position by a rivet 34. This rivet has a reduced stern portion 36 which extends downwardly through the body of the blade and at its lower end passes through the center of a cup washer 38 the body of which is countersunk in the underface 40 of the blade. This cup washer has an encircling flange 42 which lies against the underface 40 of the blade.

These flanges 42 of the cup washers have a certain thickness and the undersurface 44 of the flanges is fiat and smooth whereby'the flanges of the cup washers rest upon the drawing board surface or upon the sheet of material thereon and function as sliding feet or skids.

The pulleys 32 rotate freely on the rivets and interposed between each pulley and the underlying surface of the blade is a washer element 46 which closely embraces the stern portion of the rivet and maintains the pulley in proper position with respect to the head of the rivet.

In the apparatus here illustrated, it will be seen that the blade guiding strand 14 is attached to the drawing board by means of the fixed members 18, in a similar manner to the strand illustrated in Patent 3,251,131. As will :be readily apparent, one end of the strand is attached to a member 18 at one end of the board and adjacent to a corner, here shown as the lower corner of the board, and the strand is then carried away from the lower edge of the board to one of the pulleys 32 and around that pulley and then across the board to the diagonally located pulley 32 from which it passes toward the top of the board, around the adjacent fixed member 18 and then across the boar to the opposite fixed member 18'and down to the adjacent or uppermost one of the pulleys 32 around which it passes. From this latter pulley the strand then extends diagonally downwardly across the board to the corresponding pulley 32 at the opposite side and around this latter pulley and downwardly to the adjacent lower fixed member'lS.

By the described arrangement of the strand with respect to the board and the pulleys, it will be apparent that the straightedge may be moved up and down or back and forth from the lower or front edge of the board to the upper or back edge thereof without changing its parallel relationship with the top and bottom or front and back edges of the board.

The numeral 48 generally designates a tubular shell or crown which is locked in and extends longitudinally of the channel 28. This shell or crown is of flexible material and may be easily snapped into position by compressing the longitudinal sides'thereof, to spring the flanged lower edge portions 50 inwardly so that they can be located in the channel 28 whereupon, upon release of the compression against the sides of the channel, the flanges will move outwardly and engage the undercut faces 30 of the dovetail channel.

When the tubular shell or crown of the blade is thus placed in position the portions of the strand 14 which cross one another in the longitudinal portion of the blade above the channel, will be completely housed.

At each end of the blade there is fixed, on the top of the blade, the pulley cover or housing 52. This housing is of substantially duplicate construction with the housing illustrated in my prior Patent No. 3,251,131 with the exception that an outer side wall 54 is formed with an outwardly projecting tongue 56 which rests upon the adjacent face 26 of the blade and is secured thereto by a screw 57 or similar fastener. In other respects, the housing is of the same construction as in my prior Patent 3,251,131 in that the inner side wall 58 has the cord'opening 60 therein bordered by the outwardly projecting rim 62 while the end walls of the housing have the oppositely facing openings 64 bordered by the flanges 66. Through these latter openings the strand passes outwardly' to the fastening members 18.

In addition to the supporting skids provided by the washer flanges 42, there are provided the flat plastic skid elements 70, four of which are provided on each blade secured to the undersurface thereof. These plastic skids are approximately of the same height orthickness as the washer flanges 42 so that when the washer flanges and the plastic skids are used together both will provide a skid face for engagement with the surface of the drawing sheet. These plastic skids may be in the form of circu-' lar buttons or they may be rectangular or any other form and they may be secured by the use of a suitable adhesive or other desired securing means.

Obviously, while the washer flange forming skid and plastic skid may be used together as illustrated, they may also be used separately by providing suitable means for attaching the plastic skids, whereby the latter may be removed from the straightedge body for the use of the washer flange or washer flanges only.

It will also be understood, of course, that there will be used four of the plastic skids upon each straightedge, one adjacent to each of the four washer flanges 42.

In FIG. 8, there is illustrated another type of mounting rivet for a pulley, which may be used on a straightedge body in the four positions shown and described in connection with the pulley mounting rivet 34 and the cup washer associated therewith.

In this other or modified form of pulley mounting, the rivet is generally designated 72 and since the pulley thereon is of the same design as that previously referred to, the same reference numeral 32' is used to designate the same.

The rivet 72 has the stem portion 74 which passes downwardly through the straightedge body 20, at right angles to the sloping face or area 24 as shown.

The blade body is provided with a suitable bore 76 to receive the stem 74 and a threaded bore is formed in the end of the stem to receive the threaded shank portion 73 of the headed stud 80. Thus it will be seen that when the shank of the stud 80 is threaded into the stem of the rivet 72 it will draw the head of the rivet down toward the pulley through which the shank of the rivet passes. A suitable washer, such as a lock washer 82, encircles the shank of the rivet 72 to maintain the head of the rivet in proper Clearance with the surface 24' to permit the pulley to rotate freely. A shnilar lock washer 84 may be placed between the head of the stud 80 and the underface of the straightedge to secure the stud against accidental displacement.

In the use of this modified form of mounting rivets 72, the underface of the head of the stud may be formed smooth to provide a skid element for sliding engagement with the paper or other sheet on the drawing board or, if desired, plastic skids 84 such as those previously referred to and designated 70, may be used in combination with the studs 80.

FIG. 9 illustrates another mounting for the four pulleys carried by the straightedge wherein the inclined face or top area is built out to provide a horizontal surface over which the pulley is located. In this figure the inclined or sloping face or area of the straightedge is designated 86, the body of the straightedge being generally designated 88.

In this latter figure also the modified form of mounting for the pulley 32 is vertical or perpendicular to the hOFlzontal underface 90 of the straightedge and the stern of the rivet passes through a built-up platform or pedestal 92, the top surface of which is coplanar with the top face or area 26 of the straightedge which is located between the inclined surfaces, this top face or area corresponding to that previously referred to and designated 26.

In this modified mounting for the rivet and pulley wheel the same rivet structure is employed as shown and described in connection with FIG. 8, and accordingly the same reference numerals primed have been employed for defining corresponding portions of the structure.

In FIG. 10, there is illustrated a pedestal type support for the pulley 32' associated with the type of stem and cup washer hereinbefore described and designated by the reference characters 36 and 38. In this type support the built-up pedestal of wedge formation is designated 94 and, as in the structure shown in connection with the pedestal 92, it rests upon the inclined or sloping top surface area 96 of the straightedge body which is here designated 98. Otherwise the rivet, pulley and other parts associated with it are similar to those described in connection with FIG. 2, and the same reference numerals primed are employed for the same.

FIGS. 6 and 7 illustrate another form of skid device 6 designated to be snapped onto a straightedge body having a flat undersurface.

The snap-on skid is shown on one end of a straightedge body. Such body here is generally designated and the straightedge snap-on skid is generally designated 102.

The skid device 102 may be formed of metal or plastic and comprises or is fashioned from a strip or band of the selected material, the body of such material being designated 104.

The device 102 comprises a long bottom portion which is of a length to extend entirely across the bottom or underface or surface 108 of the straightedge body, and at each end of the bottom portion an upturned extension 119 is provided which in turn joins or continues into the upwardly sloping terminal portion 112.

The upturned ends or end walls 110 of the body 104 are of a height to raise the terminal portions 112 to an elevation which will permit these end portions to slide over the inclined or sloping surfaces 114 of the straightedge body. Thus the snap-on skids may be placed one upon each end of the straightedge or a number of them may be placed on the straightedge or they may be positioned at any location inwardly of the ends of the straightedge as desired.

To provide the desired skidding or sliding contact with the underlying surface, the body portion 104 of each of the snap-on skids is formed with a plurality of downwardly projecting circular buttons 116 shown as being three in number. These buttons may be formed in any suitable manner as, for example, by pressing the material down by suitable means whereby when the buttons are resting upon a drawing board surface or on paper on the drawing board surface each will have a very small area of contact with the surface, which may be likened to a point contact. When the underfaces of the button-like projections 116 are formed smooth or are polished, this condition, together with the point contact of the button with the underlying surface, provides a sliding support which is substantially frictionless. Thus, since the snap-on skids extend transversely or across the width of the straightedge body, the latter can be moved forward and backward or up and down without affecting the position of the skid on the straightedge since the direction of movement would be parallel to the length of the skids.

It will also be readily obvious that the snap-on skids could be positioned upon the ends of the straightedge outwardly or laterally away from the edge of a work sheet lying upon the drawing board and also outwardly or laterally of the straightedge securing strand 14.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, and since the scope of the invention is defined by the appended claims, all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents are therefore intended to be embraced by those claims.

I claim:

1. A straightedge construction for mobile drafting apparatus for use with a stationary guide cable, comprising an elongate blade body having substantially parallel longitudinal drawing instrument guiding edges, said blade body including an upper surface and a planar undersurface, a pair of pulleys adjacent each end of said blade body and spaced apart transversely thereof, and laterally inwardly of said longitudinal edges, said pulleys extending from said upper surface of said blade body and being adapted to engage said stationary guide cable, means rotatably mounting said pulleys on said blade body, said mounting means for each of said pulleys extending through said blade, and an element encircling said mounting means at the undersurface of said blade and providing, skid means therefor, the bottom surfaces of said skid means being flat and smooth and defining a plane which is paral- 7 lel to and spaced from said plane of the undersurface of said blade body, whereby said skid means is adapted for engaging a supporting surface and maintaining major portion of the undersurface of the blade body raised from such supporting surface at said longitudinal edges thereof.

2. Apparatus as defined in claim 1 wherein said skid means includes additional separate skid members secured to the undersurface of said blade body adjacent to and in spaced relationship to each of said mounting means.

3. A straightedge construction for mobi e drafting ap paratus for use with a stationary guide cable, comprising an elongate blade body having substantially parallel longitudinal drawing instrument guiding edges, said blade body including an upper surface and a planar undersurface, a pair of pulleys adjacent each end of said blade body and spaced apart transversely thereof, and laterally inwardly of said longitudinal edges, said pulleys extending from said upper surface of said blade body and being adapted to engage said stationary guide cable, means rotatably mounting said pulleys on said blade body, said mounting means for each of said pulleys extending through said blade including skid means therefor and beneath the undersurface thereof, the bottom surfaces of said skid means being Hat and smooth and defining a plane which is parallel to and spaced from said plane of the undersurface of said 'blade body, whereby said skid means is adapted for engaging a supporting surface and maintaining the major portion of the undersurface of the blade body raised from such supporting surface at said longitudinal edges thereof, means for rotatably mounting said pulleys on said blade body, said skid means comprising a portion of said mounting means extending below the undersurface of said blade body, and said mounting means including a headed member and a washer, the undersurface of a said washer being adapted to rest upon a supporting surface.

4. A straightedge construction for mobile drafting apparatus for use with a stationary guide cable, comprising an elongate blade body having substantially parallel longitudinal drawing instrument guiding edges, said blade body including upper and undersurfaces a pair of pulleys adjacent each end of said blade body and spaced apart transversely thereof, said pulleys extending from said upper surface of said blade body and being adapted to engage said stationary guide cable, and skid means supported by said blade body and extending below the undersurface of said blade body for engaging a supporting surface and maintaining the major portion of the undersurface of the blade body raised from such supporting surface at said longitudinal edges thereof, means for rotatably mounting said pulleys on said blade body, said skid means comprising .a portion of said mounting means extending below the undersurface of said blade body, and said mounting means including a headed member having a threaded bore therewithin and a threaded stud having a portion thereof threaded within said threaded bore, a portion of said threaded stud being adapted to rest upon an underlying supporting surface.

5. Apparatus as defined in claim 4 including a tapered pedestal member supported on the upper surface of said blade body for supporting an associated pulley in desired position.

6. A straightedge construction for mobile drafting apparatus for use with a stationary guide cable, comprising an elongate blade body having substantially parallel longitudinal drawing instrument guiding edges, said blade body including upper and undersurfaces a pair of pulleys adjacent each end of said blade body and spaced apart transversely thereof, said pulleys extending from said upper surface of said blade body and being adapted to engage said stationary guide cable, and skid means supported by said blade body and extending below'the undersurface of said blade body for engaging a supporting surface and maintaining the major portion of the undersurface of the blade body raised from such supporting surface at said longitudinal edges thereof, means for rotatably mounting said pulleys on said blade body, said skid'means comprising a portion of said mounting means extending below the undersurface of said blade body, and said mounting means includes a headed member and a cup washer adapted to engage an underlying supporting surface, and a tapered pedestal supported on the upper surface of said blade body for supporting an associated pulley in desired position.

References Cited UNITED STATES PATENTS 781,724 .2/1905 Holfmann 331 12 1,498,994 6/1924 Borsuk et al 33-l04 2,234,467 3/1941 De Lisle 338O X 2,246,491 6/1941 Abell 331 12 X 3,122,835 3/1964 Blodgett et a1. 3380 3,251,131 5/1966 Justis 4 3380 HARRY N. HAROIAN, Primary Examiner. 

